Components and catalysts for the polymerization of olefins

ABSTRACT

Disclosed are catalysts for the polymerization of alpha-olefins which comprise the reaction product of: 
     (a) an Al alkyl compound; 
     (b) a silicon compound containing at least a Si--OR or Si--OCOR or Si--NR 2  bond, R being a hydrocarbyl radical; 
     (c) a solid comprising, as essential support, a Mg dihalide in active form and, supported thereon, a Ti halide or a halo-Ti-alcoholate and a particular, selected type of electron-donor compound.

This application is a continuation, of application Ser. No. 08/298,514,filed Aug. 30, 1994, now abandoned which is a continuation, ofapplication Ser. No. 08/115,493, filed Sep. 1, 1993, now abandoned whichis a continuation, of application Ser. No. 07/865,804, filed Mar. 30,1992, now abandoned which is Continuation of application Ser. No.07/746,205 filed Aug. 15, 1991, which in turn is a Continuation of Ser.No. 07/582,120, filed Sep. 14, 1990, which in turn is a Continuation ofSer. No. 07/455,810, filed Dec. 26, 1989, which in turn is aContinuation of Ser. No. 07/311,370, filed Feb. 15, 1989, which in turnis a Continuation of Ser. No. 07/157,064, filed Feb. 2, 1988, which inturn is a Continuation of Ser. No. 07/029,362, filed Mar. 23, 1987,which in turn is a Continuation of Ser. No. 06/872,923, filed Jun. 11,1986, which in turn is a Continuation of Ser. No. 06,692,422, filed Jan.18, 1985, which in turn is a Continuation of Ser. No. 06,292,156, filedAug. 12, 1981 all now abandoned.

DESCRIPTION

The present invention refers to new supported components of catalystsfor the polymerization of CH₂ ═CHR olefins wherein R is an alkyl radicalwith 1 to 4 carbon atoms, or an aryl radical, and mixtures of saidolefins with ethylene; and the catalysts obtained from said components.

BACKGROUND OF THE INVENTION

The supported highly active and highly stereospecific catalysts for thepolymerization of propylene and higher olefins known up to now areobtained by the reaction of an Al alkyl compound partially complexedwith an electron-donor compound (outside donor) with a solid componentcomprising a Ti compound and an electron-donor compound (inside donor)supported on a Mg dihalide in active form.

Examples of such catalysts have been described in British Patent No.1,559,194 and Belgian Patent No. 868,682.

Outside donors consisting of silicon compounds containing Si--O--C bondshave been described, also, in published Japanese patent applications Sho79/94590 and Sho 80/36203.

Among the various and numerous inside donors such compounds asmethylmethacrylate and ethyl pivalate have been cited.

However, in all the prior art catalysts in which a silicon compoundcontaining Si--O--C bonds is used as outside donor, esters of benzoicacid and derivatives thereof are used as inside donor.

The performance of the above catalysts, expressed in terms of activityand stereospecificity, is not different from the performance of thecatalysts in which ethyl benzoate and similar esters of benzoic acid areused as outside donor.

THE PRESENT INVENTION

One object of this invention is to provide improved catalyst-formingcomponents which result in final catalysts exhibiting increased activityand stereospecificity in the polymerization of α-olefins and in whichthe inside donor is an ester different from esters of benzoic acid or ofderivatives thereof.

This and other objects are achieved by this invention in accordance withwhich, unexpectedly, it has been found that it is possible to increasethe activity and stereospecificity of the prior art supported catalystscomprising, as outside donor, a silicon compound containing Si--O--Cbonds, by using as inside donor selected esters having a particularstructure.

The catalysts of this invention comprise the product of reaction betweenthe following components:

(a) an Al trialkyl or an Al alkyl compound containing 2 or more aluminumatoms linked to each other through oxygen or nitrogen atoms or throughSO₄ or SO₃ groups;

(b) a silicon compound containing one or more Si--OR, Si--OCOR orSi--NR₂ bonds (R being a hydrocarbyl radical);

(c) a solid comprising, as essential support, an anhydrous Mg dihalidepresent in active form and, supported on said dihalide, a Ti-halide or aTi-haloalcoholate and an electron-donor compound selected from thefollowing groups of compounds:

(1) mono and diesters of aromatic dicarboxylic acids having the COOHgroups in ortho position, wherein the R hydrocarbyl radicals of the COORgroups contain less than 3 carbon atoms and at least one of said Rradicals contains 2 carbon atoms;

(2) esters of saturated and unsaturated carboxylic acids of formulaRCOOR' wherein the R hydrocarbyl radical is either a saturated orunsaturated branched radical containing from 3 to 20 carbon atoms or anarylalkyl radical with 7 to 20 carbon atoms or an aryl radical with 3 to20 carbon atoms linked to the esteric carbonyl group directly or througha methylene group and in which R' is a hydrocarbyl radical with lessthan 3 carbon atoms.

Representative compounds, which are also the preferred compounds, arethe following: diethylphthalate, methylethylphthalate,diethyl-2,3-naphthalendicarboxylate, methyl and ethyl pivalate, methyland ethyl methacrylate.

As indicated, the esters of the polycarboxylic acids can contain, besidethe ester groups, also unesterified COOH groups.

In preparing component (c) the esters are contacted with the active Mgdihalide, or the precursors of said dihalides as preformed compounds, orthe esters can be formed in situ by means of known reactions as, forinstance, by esterification between an alcohol or an alcoholate and anaryl halide or between an anhydride or a hemiester of a polycarboxylicacid with an alcohol, or by transesterification. The esters can also beused in mixture with other known inside donors.

The active anhydrous Mg dihalides forming the essential support ofcomponent (c) are the Mg dihalides showing in the X-rays powder spectrumof component (c) a broadening of at least 30% of the most intensediffraction line which appears in the powder spectrum of thecorresponding dihalide having 1 m² /g of surface area or are the Mgdihalides showing an X-rays powder spectrum in which said most intensediffraction line is replaced by a halo with the intensity peak shiftedwith respect to the interplanar distance of the most intense line and/orare the Mg dihalides having a surface area greater than 3 m² /g.

The measurement of the surface area of the Mg dihalides is made oncomponent (c) after treatment with boiling TiCl₄ for 2 hours. The foundvalue is considered as surface area of the Mg dihalide.

Very active forms of Mg dihalides are those showing an X-rays powderspectrum in which the most intense diffraction line appearing in thespectrum of the corresponding halide having 1 m² /g of surface area isdecreased in relative intensity and broadened to form a halo or arethose in which said most intense line is replaced by a halo having itsintensity peak shifted with respect to the interplanar distance of themost intense line. Generally, the surface area of the above forms ishigher than 30-40 m² /g and is comprised in particular between 100-300m² /g.

Active forms are also those deriving from the above forms byheat-treatment in inert hydrocarbon solvents and showing, in the X-raysspectrum, sharp diffraction lines in place of the halos.

The sharp, most intense line of these forms shows a broadening of atleast 30% with respect to the corresponding line of the Mg dihalidehaving 1 m² /g of surface area. Preferred Mg dihalides are Mg dichlorideand Mg dibromide. The content in water of the dihalides is generallyless than 1% by weight.

By Ti halides or Ti haloalcoholates and esters supported on the activeMg dihalide is meant the above compounds which may be chemically orphysically fixed on the support, and not extractable from component (c)by treatment of the same with boiling 1,2-dichloroethane for 2 hours.

Components (a), (b) and (c) are made to react with each other in anyorder; preferably, however, components (a) and (b) are premixed beforebeing contacted with component (c).

Component (c) may be premixed with either component (a) and/or (b). Thepre-mixing of (a) and (b) is conducted at temperatures comprised,usually, between room temperature and the temperature used in thepolymerization process.

The pre-reaction of (c) and (b) may be carried out also at highertemperatures. Also, compound (b) may be incorporated and made to reactwith component (c) itself. Component (b) is made to react in a molarratio with respect to the halogenated Ti compound supported on component(c) of at least 1 and in a molar ratio with respect to the Al alkylcompound used as component (a) of less than 20 and, preferably,comprised between 0.05 to 0.3.

In component (c), the molar ratio between the Mg dihalide and thehalogenated Ti compound supported thereon is comprised between 1 and 500and the molar ratio between said halogenated Ti compound and theelectron-donor supported on the Mg dihalide is comprised between 0.1 and50.

The silicon compounds set forth in (b) include compounds of generalformula:

    R.sub.m SiY.sub.n X.sub.p

wherein:

R is an alkyl, alkenyl, aryl, arylalkyl, cycloalkyl radical with from 1to 20 carbon atoms;

Y is --OR', --OCOR' or --NR'₂ wherein R', either equal to or differentfrom R, has the same meaning as R;

X is either a halogen or hydrogen atom or a --OCOR" or --NR₂ " groupwherein R", either equal to or different from R' has the same meaning asR';

m, n and p are numbers comprised respectively between: m between 0 and3, n between 1 and 4 and p between 0 and 1; and m+n+p is equal to 4.

Other silicon compounds that may be used are compounds in which two ormore silicon atoms are bound to each other through oxygen or nitrogenatoms.

Examples of these compounds are hexaethoxydisiloxane, and symmetricaldiphenyltetraethoxydisiloxane ##STR1##

Preferred silicon compounds are: phenylalkoxysilanes, such asphenyltriethoxy or trimethoxysilane, diphenyldimethoxy anddiethoxysilane, monochlorophenyldiethoxysilane; alkylalkoxysilanes as,for instance, ethyltriethoxysilane and ethyltriisopropoxysilane.

Examples of other suitable compounds are: chlorotriethoxysilane,acetoxytriethoxysilane, vinyltriethoxysilane, butyltriethoxysilane,triphenylmonoethoxysilane, phenyltricycloethoxysilane,phenyldiethoxydiethylaminosilane, tetraphenoxysilane ortetralkoxysilanes such as tetramethoxysilane.

The silicon compound can also be formed in situ by reaction, forinstance, of a halogenated silicon compound such as SiCl₄ with analcohol or an alcoholate of Mg or Al.

In the catalysts of the invention, the silicon compound is present, in acombined form in the solid product of the reaction between the variouscatalyst forming components, in a molar ratio between the siliconcompound and the halogenated Ti compound greater than 0.05 and generallycomprised between 0.1 and 5.

The Al alkyl compounds forming component (a) include Al trialkyls as,for instance, Al triethyl, Al triisobutyl, Al triisopropyl, andcompounds containing two or more Al atoms linked to each other throughhetero-atoms as: ##STR2##

As indicated, Al alkyl compounds in which Al atoms are linked throughgroups such as SO₄ or SO₃ are also suitable.

The Al alkyl compounds may be used in mixture with Al alkyl halides,such as AlEt₂ Cl.

Component (c) is prepared according to known methods. One of thesemethods consists in co-milling the Mg halide and the electron-donorcompound of this invention until the appearance in the X-ray spectrum ofthe milled product of the modifications set forth above for the spectrumof the Mg dihalide and thereafter reacting the milled product with theTi compound.

Preparations of this type are described in British Patent No. 1,559,194.

Similar preparations are described in U.S. Pat. Nos. 4,107,413,4,107,414 and 4,107,415.

Another method consists in reacting the adduct of a Mg halide and analcohol with a Ti compound in the presence of an electron-donor compoundnot containing active hydrogen atoms. This method is described inBelgian Patent No. 868,682.

According to another method, which is described in published Germanpatent application No. 3,022,738, the adduct between the Mg dihalide andthe alcohol is reacted in liquid form with the halogenated Ti compoundand the electron-donor compound.

Further methods are described in published German application No.2,924,029, U.S. Pat. No. 4,220,554, as well as in Italian patentapplication No. 27,261/79, the latter being the priority document forthe pending U.S. application of Antonio Monte, Ser. No. 206,541, filedNov. 13, 1980 now U.S. Pat. No. 4,328,122.

Another method consists in co-milling the Mg dihalide, the halogenatedTi compound and the electron-donor compound until the Mg dihalide isactivated, and in treating a suspension of the milled product in ahalogenated hydrocarbon such as 1,2-dichloroethane, chlorobenzene,methylene chloride, hexachloroethane.

The treatment is carried out at temperatures comprised between 40° C.and the boiling point of the halogenated hydrocarbon for a time ranging,in general, from 1 to 4 hours.

According to another method, a porous support like SiO₂ or Al₂ O₃,having a low content of OH groups (preferably less than 1% by weight),is impregnated with a liquid adduct between the Mg dihalide and analcohol; the support is then treated with an excess of TiCl₄ containing,dissolved therein, the electron-donor compound according to theprocedure described, for instance, in published German patentapplication No. 3,022,738 or Belgian patent No. 868,682.

In all the above methods, the final product contains a Mg dihalide,present in the active form as set forth hereinabove.

Other known methods which lead to the formation of Mg dihalide in activeform or to Ti-containing Mg dihalide supported components, in which thedihalide is present in active form, are based on the followingreactions:

reaction of a Grignard reagent or a MgR₂ compound (R being a hydrocarbylradical) or complexes of said MgR₂ compounds with Al trialkyls, withhalogenating agents, such as AlX₃ or AlR_(m) X_(n) compounds (X ishalogen, R is a hydrocarbyl, m+n=3), SiCl₄ or HSiCl₃ ;

reaction of a Grignard reagent with a silanol or polysiloxane, H₂ O orwith an alcohol and further reaction with a halogenating agent or withTiCl₄ ;

reaction of Mg with an alcohol and a halogenhydric acid or of Mg with ahydrocarbyl halide and an alcohol;

reaction of MgO with Cl₂ or AlCl₃ ;

reaction of MgX₂.nH₂ O (X=halogen) with a halogenating agent or TiCl₄ ;

reaction of Mg mono- or dialcoholates or Mg carboxylates with ahalogenating agent.

The Ti halides and Ti halogenalcoholates include, in particular, the Titetrahalides, Ti trihalides and Ti trihalogenalcoholates. Preferredcompounds are: TiCl₄, TiBr₄, 2,6-dimethylphenoxytrichlorotitanium.

The Ti trihalides are obtained according to known methods, for instanceby reduction of TiCl₄ with Al or an organometallic Al compound or withhydrogen.

In the case of Ti trihalides, it may be convenient, for the purpose ofimproving the performance of the catalysts, to carry out an oxidization,even if partial, of the titanium, either during or after the preparationof component (c). For this purpose there may be used halogens, iodinehalides.

Preferred catalysts are those in which: component (c) is obtained fromMgCl₂, TiCl₄ and diethyl phthalates or methyl or ethyl pivalates, and inwhich component (b) is phenyl or ethyltriethoxysilane ordiphenyldimethoxy or diethoxysilane.

Component (a) is an Al trialkyl such as Al triethyl or Al triisobutyl.

Component (c) is prepared according the methods described in Britishpatent No. 1,559,194, Belgian patent No. 868,682, published Germanapplication No. 2,924,029, U.S. Pat. No. 4,220,554, Italian patentapplication 27,261/79 or published German application 3,022,738.

The preferred method of preparing component (c) includes also theco-milling of MgCl₂, TiCl₄ and the ester and in treating the milledproduct with a halogenated hydrocarbon such as 1,2-dichloroethane.

The catalysts according to the invention are useful for polymerizing thealpha-olefins according to known methods that is, by carrying out thepolymerization in a liquid phase, either in the presence or absence ofan inert hydrocarbon solvent, or in gas phase or also by combining, forinstance, a liquid phase polymerization step with a step in gas phase.

In general the polymerization temperature is comprised between 40° and160° C., but preferably between 60° and 90° C., operating either atatmospheric or at greater than atmospheric pressure.

As a molecular weight regulator hydrogen or other regulators of a knowntype are used.

The catalysts are particularly suitable for polymerizing propylene,butene-1, styrene, 4-methylpentene. The catalysts may also be usedaccording to known methods to polymerize mixtures of propylene andethylene to form modified polypropylenes having better shock-resistanceat low temperatures (the so-called block copolymers of propylene andethylene) or to obtain random crystalline copolymers of propylenecontaining minor proportions of polymerized ethylene.

The following examples are given for merely illustrative purpose and arenot intended to be in any way limiting of the scope of the invention.

EXAMPLES 1-2

Into a stainless stell autoclave having a total volume of 3 l, equippedwith a magnetized stirrer and a thermocouple heat-stabilized at 60° C.and kept under pressure by a nitrogen atmosphere, there were introduced1,000 ml of a suspension of 5 mols of triethyl aluminum in degassed andanhydrous n-heptane, the phenyltriethoxysilane (PES) and a solidcatalytic component prepared according to Example 1 of Italian patentapplication No. 27,621/79, but using, instead of ethylbenzoate, theesters listed in Table I, while propylene was also fed in. The catalyticcomponents thus prepared showed X-rays powder spectrum in which the mostintense diffraction line appearing in the spectrum of MgCl₂ having 1 m²/g of surface area was decreased in relative intensity and broadened toform a halo.

After closing the autoclave, hydrogen was introduced up to a pressure of0.2 atmospheres, the temperature was brought to 70° C. and,simultaneously, propylene was introduced up to a total pressure of 7atmospheres.

During the polymerization, the pressure was kept constant by continuousfeeding of the monomer. After 4 hours, the polymerization was stopped byquick cooling and degassing of the polymeric slurry. The polymer wasseparated from the solvent by filtering and was dried in a hot nitrogenflow at 70° C. The quantity of polymer dissolved in the filtrate wasthereupon isolated, weighed and summed to the polymer soluble in boilingn-heptane, for calculation of the isotacticity index (I.I.).

The quantity of catalytic component used and the content of Ti in saidcomponent, the molar ratio of the phenyltriethoxysilane with respect tothe triethylaluminum, the yield in polymer with respect to theintroduced catalytic component, the isotacticity index (I.I.), thesurface area of the solid catalytic component and the inherent viscositydetermined in tetralin at 135° C., are all reported in Table I.

EXAMPLE 3

Example 1 was repeated but using a solid catalytic component prepared asfollows:

anhydrous MgCl₂, an ester, listed in Table II, and TiCl₄ in molar ratioof 1:1 with respect to the ester, was co-ground in a vibrating mill ofthe type VIBRATOM manufactured by N. V. Tema, s'Gravenhage, Holland,having a total volume of one liter and containing 3 kg of stainlesssteel balls of 16 mm diameter;

a filling coefficient equal to 100 g/g of total volume (vacuum) wasused. The interior temperature of the mill was 25° C., and the grindingtime was 72 hours;

charging of the mill, the grinding and discharging of the mill occurredin a nitrogen atmosphere.

10 g of the co-ground product was contacted with 100 ml of1,2-dichloroethane at 80° C. for 2 hours. After this period,1,2-dichloroethane was removed by filtration at 80° C. and the residualsolid product was repeatedly washed with n-heptane at room temperatureuntil the chlorine ions disappeared from the filtrate and then was keptin suspension in heptane.

The catalytic component thus prepared gave an X-rays powder spectrum inwhich the most intense diffraction line appearing in the spectrum ofMgCl₂ having 1 m² /g of surface area was decreased in relative intensityand broadened to form a halo.

The ester, the characteristics of the solid catalytic component, and theresults of the polymerization test are reported in Table I.

EXAMPLE 4

Example 1 was repeated but using a solid catalytic component preparedaccording to Example 3 of Italian patent application No. 26,908 A/78,which is the priority document for the pending U.S. application of MarioFerraris et al Ser. No. 226,837 filed Jan. 21, 1981, now U.S. Pat. No.4,399,054.

A solid adduct MgCl₂.3C₂ H₅ OH in the form of spherical particles wasslowly added to a suspension of an adduct TiCl₄ -ester using molarratios Mg/ester of 6 and TiCl₄ /C₂ H₅ OH of 12.

The whole was heated at 100° C., kept at said temperature for 2 hoursand then filtered at 100° C. The resulting solid product was treatedwith 110 ml of TiCl₄ at 120° C. for 2 hours. After this period, TiCl₄was removed by filtration and the solid was washed with n-heptane attemperatures decreasing from 90° C. to room temperature until thechlorine ion disappeared and then kept in heptanic suspension.

The catalytic component thus prepared gave the same X-rays spectrum asthe catalytic component of Example 1.

The ester, the characteristics of the solid catalytic component and theresults of the polymerization tests have been reported in Table I.

COMPARATIVE EXAMPLES 1 AND 2

Example 1 was repeated but using the solid catalytic component preparedaccording to Example 1 of Italian Patent application No. 27,261/79. TheX-rays powder spectrum was similar to that of the catalytic component ofExample 1.

The results of the polymerization tests are reported in Table I.

COMPARATIVE EXAMPLE 3

Example 4 was repeated but using a solid catalytic component preparedaccording to Example 3 of Italian patent application No. 26,908 A/78.The X-rays spectrum of that catalytic component was similar to those ofExamples 1-2.

The characteristics of the solid product and the results of thepolymerization tests are reported in Table I.

                                      TABLE I                                     __________________________________________________________________________    Solid catalytic component   Polymerization                                                   MgCl.sub.2                                                                          Ti content        Yield                                                 ester of solid                                                                             Al(C.sub.2 H.sub.5).sub.3                                                                g polymer                              Example        grinding                                                                            component %                                                                          PES   Catalyst                                                                           g catalyst                                                                          I. I.                                                                            η in h                    No.  Ester     mols/mols                                                                           by weight                                                                            mols/mols                                                                           mg   component                                                                           %  dl/g                          __________________________________________________________________________    1    diethylphthalate                                                                        14    2.3    20    50   7,800 93.3                                                                             1.4                           2    ethylmethacrylate                                                                       7     2.9    10    47   7,000 90.7                                                                             1.3                           3    ethylbenzoylacetate                                                                     7     2.2    10    43   4,900 95.4                                                                             1.2                           4    monoethylphthalate                                                                      6     2.8    20    26   6,000 96.9                                                                             1.3                           comp. 1                                                                            ethylbenzoate                                                                           7     2.0    10    46   6,000 90,6                                                                             1.4                           comp. 2                                                                            ethylbenzoate                                                                           7     2.0    5     47   4,000 92.7                                                                             1.6                           comp. 3                                                                            ethylbenzoate   3.8    3     45   4,500 94 1.5                           __________________________________________________________________________

What is claimed is:
 1. Catalysts for the polymerization of alpha-olefinscomprising the product of reaction of the following components:a) an Altrialkyl or an Al alkyl compound containing two or more Al atoms linkedto each other through an oxygen or a nitrogen atom or through SO₄ or SO₃groups; b) a silicon compound containing one or more Si--R, Si--OCOR orSi--NR₂ bonds, R being a hydrocarbyl radical, selected from compoundshaving the formula

    R.sub.m SiY.sub.n X.sub.p

wherein:R is an alkyl, alkenyl, aryl, arylalkyl, or cycloalkyl radicalwith from 1 to 20 carbon atoms; Y is --OR', --OCOR' or --NR'₂ whereinR', either equal to or different from R, has the same meaning as R; X iseither a halogen or a hydrogen atom or a --OCOR" or NR"₂ group whereinR", either equal to or different from R', has the same meaning as R'; m,n and p are numbers between 0 and 3 for m, between 1 and 3 for n, andbetween 0 and 1 for p, with m+n+p being equal to 4; and c) a solidcomponent comprising an anhydrous Mg dihalide in active form, asessential support, and, supported on said Mg dihalide, a Ti halide orhaloalcoholate and an electron donor compound which is diethylphthalate.2. Catalysts as defined in claim 1, in which the silicon compound ofcomponent (b) is a phenyl trialkoxysilane or a diphenyldialkoxysilane oran alkyl di- or trialkoxysilane.
 3. A catalyst according to claim 1, inwhich the Ti compound is TiCl₄ and the Mg dihalide is MgBr₂.
 4. Thecatalyst of claim 1, wherein the Mg dihalide is MgCl₂.
 5. The catalystof claim 1, wherein the Ti halide or haloalcoholate is TiCl₄.
 6. Processfor the polymerization of alpha-olefins CH₂ ═CHR in which R is an alkylradical with 1 to 4 C or an aryl radical and mixtures of said olefinswith ethylene, characterized in that the polymerization process iscarried out in liquid phase in the presence or absence of an inerthydrocarbon solvent or in gas phase, in the presence of a catalyst asdefined in claim 1.